2009/10/25 <span dir="ltr"><<a href="mailto:hollunder@gmx.at">hollunder@gmx.at</a>></span><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">On Sun, 25 Oct 2009 11:40:16 +0100<br>
rosea grammostola <<a href="mailto:rosea.grammostola@gmail.com">rosea.grammostola@gmail.com</a>> wrote:<br>
<br>
> Hi,<br>
><br>
> I found this info:<br>
><br>
><br>
> "USB and jack<br>
><br>
> The USB interrupt period is 1 msec. To be able to get lower latency<br>
> with jack when using it with an USB device, you have to use a setting<br>
> as 48kHz and 3 period. It will makes the buffer time a multiple of 1<br>
> msec and you will get a much lower latency as with the default 2<br>
> period. Additionaly, loading the snd-usb-audio with the parameter<br>
> "nrpacks=1" will give you a much lower latency (for this to work take<br>
> care that CONFIG_USB_BANDWIDTH is not set and<br>
> CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)."<br>
><br>
><br>
> <a href="http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_jack" target="_blank">http://proaudio.tuxfamily.org/wiki/index.php?title=Howto_RT_Kernel#USB_and_jack</a><br>
><br>
><br>
> 1) is this info still up-to-date?<br>
> 2) how do I exactly take care of this:<br>
> "Additionaly, loading the snd-usb-audio with the parameter<br>
> "nrpacks=1" will give you a much lower latency (for this to work take<br>
> care that CONFIG_USB_BANDWIDTH is not set and<br>
> CONFIG_USB_DYNAMIC_MINORS is not set in your running kernel)"<br>
><br>
> (Debian (based) systems)<br>
><br>
> \r<br>
<br>
</div>In my experience 48kHz/3 periods works a bit more stable, the possible<br>
latency settings in jack don't really change, 64 frames is still the<br>
lower boundary and unstable.<br>
<br>
But I haven't heard about 2) and am very curious about this myself.<br>
<br>
Philipp</blockquote><div><br></div><div>2) Edit /etc/modprobe.conf or /etc/modprobe.d/modprobe.conf with:</div><div><br></div><div>options snd-usb-audio nrpacks=1</div><div><br></div><div>And to "make sure". you have to have the kernel options changed. make menuconfig, and press "/" to search for the two options.</div>
<div><br></div><div>Philipp: we already dealt with that one but _without_ substantial cause-and-effect <a href="http://bugs.archaudio.org/task/5">http://bugs.archaudio.org/task/5</a></div></div>